Age-related differences in total and regional bone mass: a cross-sectional study with DXA in 429 normal women

Quantitative computed tomography has higher sensitivity detecting critical bone mineral density compared to dual-energy X-ray absorptiometry in postmenopausal women and elderly men with osteoporotic fractures: a real-life study

INTRODUCTION

Dual-energy X-ray absorptiometry (DXA) is considered the gold standard for the diagnosis of osteoporosis and assessment of fracture risk despite proven limitations. Quantitative computed tomography (QCT) is regarded as a sensitive method for diagnosis and follow-up. Pathologic fractures are classified as the main clinical manifestation of osteoporosis. The objective of the study was to compare DXA and QCT to determine their sensitivity and discriminatory power.

MATERIALS AND METHODS

Patients aged 50 years and older were included who had DXA of the lumbar spine and femur and additional QCT of the lumbar spine within 365 days. Fractures and bone mineral density (BMD) were retrospectively examined. BMD measurements were analyzed for the detection of osteoporotic fractures. Sensitivity and receiver operating characteristic curve were used for calculations. As an indication for a second radiological examination was given, the results were compared with control groups receiving exclusively DXA or QCT for diagnosis or follow-up.

RESULTS

Overall, BMD measurements of 404 subjects were analyzed. DXA detected 15 (13.2%) patients having pathologic fractures (n = 114) with normal bone density, 66 (57.9%) with osteopenia, and 33 (28.9%) with osteoporosis. QCT categorized no patients having pathologic fractures with healthy bone density, 14 (12.3%) with osteopenia, and 100 (87.7%) with osteoporosis. T-score DXA, trabecular BMD QCT, and cortical BMD QCT correlated weakly. Trabecular BMD QCT and cortical BMD QCT classified osteoporosis with decreased bone mineral density (AUC 0.680; 95% CI 0.618-0.743 and AUC 0.617; 95% CI 0.553-0.682, respectively). T-score DXA could not predict prevalent pathologic fractures. In control groups, each consisting of 50 patients, DXA and QCT were significant classifiers to predict prevalent pathologic fractures.

CONCLUSION

Our results support that volumetric measurements by QCT in preselected subjects represent a more sensitive method for the diagnosis of osteoporosis and prediction of fractures compared to DXA.

Comparison of Bioelectrical Impedance Analysis and Dual Energy X-ray Absorptiometry for Total and Segmental Bone Mineral Content with a Three-Compartment Model

Modern bioelectrical impedance analysis (BIA) provides a wide range of body composition estimates such as fat mass (FM), lean body mass (LBM), and body water, using specific algorithms. Assuming that the fat free mass (FFM) and LBM can be accurately estimated by the 8-electrode BIA analyzer (BIA_8MF; InBody230, Biospace), the bone mineral content (BMC) may be calculated by subtracting the LBM from the FFM estimates based on the three-compartment (3C) model. In this cross-sectional study, 239 healthy Taiwanese adults (106 male and 133 female) aged 20-45 years were recruited for BIA and dual-energy X-ray absorptiometry (DXA) measurements of the whole body and body segments, with DXA as the reference. The results showed a high correlation between BIA_8MF and DXA in estimating total and segmental LBM, FM and percentage body fat (r = 0.909-0.986, 0.757-0.964, and 0.837-0.936, respectively). For BMC estimates, moderate to high correlations (r = 0.425-0.829) between the two methods were noted. The percentage errors and pure errors for BMC estimates between the methods ranged from 33.9% to 93.0% and from 0.159 kg to 0.969 kg, respectively. This study validated that BIA_8MF can accurately assesses LBM, FM and body fat percentage (BF%). However, the estimation of segmental BMC based on the difference between FFM and LBM in body segments may not be reliable by BIA_8MF.

Biological sex variation in bone mineral density in the cranium and femur

OBJECTIVES

Sex and age trends in bone mineral density (BMD) play an important role in the estimation of age-at-death (AAD) of unidentified human remains. Current methodologies lack the ability to precisely estimate age in older individuals. In this study, BMD of the cranium and femur measured by DXA were examined to establish their applicability for age estimation in older adults. BMD as measured by DXA, is most commonly used clinically for prediction of osteoporotic fracture risk. We hypothesized that weight-bearing and non-weight-bearing bones, the femur and cranium, respectively, would provide valuable insights for aging.

METHODS

The sample consists of 32 sets of excised cranial fragments from the Regional Forensic Center, Johnson City, Tennessee and 41 associated crania and femora from the North Carolina Office of the Chief Medical Examiner. All crania and femora were scanned using a Hologic (R) DXA scanner and data were analyzed using Student t-tests, Loess regression, and ANOVA.

RESULTS

Student t-tests indicate a significant relationship between the sexes and cranial BMD and a significant relationship between age cohorts and femoral neck BMD. The Loess regression showed different aging patterns in the cranium for females and males older than 55. And the ANOVA showed changes in femoral neck after age 55.

CONCLUSIONS

These results indicate age and sex dependent changes in BMD especially for individuals over the age of 55, which offers improvement from current aging methods for older individuals. Further research using a larger sample size could improve the predictive capabilities of the model.

Association of eating out with bone density in Taiwan

OBJECTIVE

The present study analysed data derived from the 2004-2008 Nutrition and Health Survey in Taiwan, conducted by the Ministry of Health and Welfare, to understand the relationship among eating-out behaviour, related non-nutritional factors and osteopenia in the Taiwanese population. Design/Setting/Subjects Data of 1140 adults who had been evaluated with dual-energy X-ray absorptiometry in June 2007 were included. The data were analysed through descriptive and inferential statistics to determine the association of osteopenia with the frequency of eating out, demographic variables (i.e. age, sex, level of education, marital status and place of birth), BMI, waist circumference and food consumption.

RESULTS

Gender, age, education level, personal income and waist circumference were all factors found to be significantly associated with eating-out frequency and the incidence of osteopenia. Eating-out frequency was negatively associated with the incidence of osteopenia. Individuals with BMI>27 kg/m2 had a lower frequency of eating out and a lower incidence of osteopenia. Individuals with a lower monthly income had a significantly greater chance of developing osteopenia. Men living without spouses had significantly higher chances of osteopenia. Ca intake was negatively associated with breakfast eating-out frequency.

CONCLUSIONS

Eating-out frequency was not associated with an increasing incidence of osteopenia, but affected the Ca intake in the Taiwanese population. Having a balanced selection of food is crucial to reduce the incidence of osteopenia. Improving nutritional knowledge for those under higher risk of osteopenia is necessary to prevent osteopenia and Ca deficiency.

Energy expenditure and aging

The study of energy expenditure (EE) has deep roots in understanding aging and lifespan in all species. In humans, total EE decreases substantially in advanced age resulting from parallel changes in resting metabolic rate (RMR) and activity EE. For RMR, this reduction appears to be due to a reduction in organ mass and specific metabolic rates of individual tissues. However, these anatomical changes explain very little regarding the decline in activity EE, which is governed by both genetic and environmental sources. The biological control centers for activity EE are closely coupled with body mass fluctuations and seem to originate in the brain. Several candidate neuromodulators may be involved in the age-related reduction of activity EE that include: orexin, agouti-related proteins and dopaminergic pathways. Unfortunately, the existing body of research has primarily focused on how neuromodulators influence weight gain and only a few studies have been performed in aging models. Recent evidence suggests that activity EE has an important role in dictating lifespan and thus places emphasis on future research to uncover the underlying biological mechanisms. The study of EE continues to unlock clues to aging.

Age, gender, and race/ethnic differences in total body and subregional bone density

SUMMARY

Total body bone density of adults from National Health and Nutrition Examination Survey (NHANES) 1999-2004 differed as expected for some groups (men>women and blacks>whites) but not others (whites>Mexican Americans). Cross-sectional age patterns in bone mineral density (BMD) of older adults differed at skeletal sites that varied by degree of weight-bearing.

INTRODUCTION

Total body dual-energy X-ray absorptiometry (DXA) data offer the opportunity to compare bone density of demographic groups across the entire skeleton.

METHODS

The present study uses total body DXA data (Hologic QDR 4500A, Hologic, Bedford MA, USA) from the NHANES 1999-2004 to examine BMD of the total body and selected skeletal subregions in a wide age range of adult men and women from three race/ethnic groups. Total body, lumbar spine, pelvis, right leg, and left arm BMD and lean mass from 13,091 adults aged 20 years and older were used. The subregions were chosen to represent sites with different degrees of weight-bearing.

RESULTS

Mean BMD varied in expected ways for some demographic characteristics (men>women and non-Hispanic blacks>non-Hispanic whites) but not others (non-Hispanic whites>Mexican Americans). Differences in age patterns in BMD also emerged for some characteristics (sex) but not others (race/ethnicity). Differences in cross-sectional age patterns in BMD and lean mass by degree of weight-bearing in older adults were observed for the pelvis, leg, and arm.

CONCLUSION

This information may be useful for generating hypotheses about age, race, and sex differences in fracture risk in the population.

Body composition in the SOS (Swedish Obese Subjects) reference study

OBJECTIVE

The primary objective was to establish population-based, sex- and age-specific reference data with respect to body composition variables. Secondary objectives were to relate body mass index (BMI) to anthropometric measurements reflecting central adiposity and to body fat (BF). Another objective was to examine if secular changes in adipose tissue distribution occurred during the sampling period, 1994-1999.

DESIGN

Sex- and age-specific data on anthropometric measurements and body composition were cross-sectionally collected in the reference study of Swedish Obese Subjects.

SUBJECTS

In total, 1135 randomly selected subjects (524 men and 611 women), aged 37-61 y, BMI 17.6-45.4 kg/m(2).

MEASUREMENTS

Measures of body fatness and fat distribution (by dual energy X-ray absorptiometry and anthropometry) were collected.

RESULTS

At BMI 25 kg/m(2), relative (absolute) BF mass was 24% (19 kg) in men vs 36% (25 kg) in women, waist circumference was 90 vs 85 cm, and sagittal trunk diameter was 21 vs 19 cm. BF and measures of centralized adipose tissue distribution increased with age in both sexes (P<0.01). In women, waist circumference and sagittal diameter increased (P<0.01) over the sampling period while BMI did not.

CONCLUSIONS

Sex- and age-specific reference data on body composition are reported from a randomly selected sample of Swedish men and women. At given BMIs, women had more BF but smaller waist circumference than men. Secular increases in indices of central obesity were found in women but not in men.

Reference curve of bone ultrasound measurements in proximal phalanges in normal Spanish women

There are clear discrepancies in how the different measurements of phalangeal bone ultrasound, such as the amplitude-dependent speed of bone ultrasound (Ad-SoS), correlate with age, given their dependence on gonadal status and other anthropometric variables. In order to contribute to clarifying these discrepancies, we evaluated the phalangeal Ad-SoS in healthy women-295 postmenopausal, 59 perimenopausal, and 270 premenopausal. Phalanges (II-V) of the nondominant hand were measured and the mean Ad-SoS was computed. There were significant differences between groups (p < 0.0001 in all cases), with the perimenopausal group presenting the intermediate values. For the overall group of women, the Ad-SoS was significantly and negatively correlated with age, weight, and body mass index (BMI), and positively correlated with height (p < 0.0001 in all cases). By gonadal status group, the premenopausal women showed the three significant negative correlations of Ad-SoS with age, weight, and BMI (each, p < 0.0001), the perimenopausal group only with BMI (p < 0.007), and the postmenopausal group with age and BMI (p < 0.0061 to p < 0.0001) and also with years since menopause (p < 0.0001). The premenopausal decline in AD-SoS requires further longitudinal studies, although in our experience it may depend on dietary habits and/or a diminished quality, though not quantity, of bone in this period of a woman's fertile life.

The effect of menopause on regional and total body lean mass

OBJECTIVES

To investigate the effect of menopause on regional and total body lean mass.

METHODS

Evaluation of 123 healthy premenopausal women (40.6 +/- 10.8 years) and 123 healthy postmenopausal women (61.8 +/- 7.5 years). All subjects were right side dominant. Regional (head, bilateral arms, trunk, and bilateral legs) and total body lean mass were measured using whole-body scanning by dual-energy X-ray absorptiometry. Baseline characteristics including age, height, weight, and menopausal state were recorded. These variables were compared between pre- and postmenopausal women. In all subjects, correlations between regional or total body lean mass and baseline characteristics were investigated using univariate and multiple regression analyses.

RESULTS

Height, and lean mass of the trunk, bilateral legs and total body were significantly lower in postmenopausal women than in premenopausal women, while lean mass of the bilateral arms did not differ between the two groups. On univariate regression analysis, bilateral arms lean mass was positively correlated with height (P < 0.001). Trunk, bilateral legs, and total body lean mass were inversely correlated with age and menopausal state (P < 0.001), but were positively correlated with height (P < 0.001). After adjusting for age and height, trunk lean mass was still correlated with menopausal state (P < 0.01).

CONCLUSIONS

Menopause induces lean mass loss, independent of aging and height. Trunk lean mass is more prone to decline with menopause than lean mass of other sites.

Gender-related differences in the relationship between densitometric values of whole-body bone mineral content and lean body mass in humans between 2 and 87 years of age

The mineral, lean, and fat contents of the human body may be not only allometrically but also functionally associated. This report evaluates the influence of muscle mass on bone mass and its age-related changes by investigating these and other variables in both genders in the different stages of reproductive life. We have analyzed the dual-energy X-ray absorptiometry (DEXA)-determined whole-body mineral content (TBMC), lean body mass (LBM), and fat body mass data (FBM) of 778 children and adolescents of both genders, aged 2-20 years [previously reported in Bone 16(Suppl.): 393S-399S; 1995], and of 672 age-matched men and women, aged 20-87 years. Bone mass (as assessed by TBMC) was found to be closely and linearly associated with muscle mass (as reflected by LBM) throughout life. This relationship was similar in slope and intercept in prepubertal boys and girls. However, while keeping the same slope of that relationship (50-54 g increase in TBMC per kilogram LBM): (1) both men and women stored more mineral per unit of LBM within the reproductive period than before puberty (13%-29% and 33%-58%, respectively); (2) women stored more mineral than age-matched men with comparable LBM (17%-29%) until menopause; and (3) postmenopausal women had lower values of bone mineral than premenopausal women, similar to those of men with comparable LBM. Men showed no age effect on the TBMC/LBM relationship after puberty. Multiple regression analyses showed that not only the LBM, but also the FBM and body height (but not body weight), influenced the TBMC, in that decreasing order of determining power. However, neither the FBM nor body height could explain the pre/postpubertal and the gender-related differences in the TBMC/LBM relationship. Accordingly: (1) calculated TBMC/LBM and FBM-adjusted TBMC/LBM ratios were lower in girls and boys from 2-4 years of age until puberty; (2) thereafter, females rapidly reached significantly higher ratios than age-matched men until menopause; and (3) then, ratios for women and age-matched men tended to equalize. A biomechanical explanation of those differences is suggested. Sex hormones or related factors could affect the threshold of the feedback system that controls bone remodeling to adapt bone structure to the strains derived from customary mechanical usage in each region of the skeleton (bone "mechanostat"). Questions concerning whether the mineral accumulation in women during the reproductive period is related or not to an eventual role in pregnancy or lactation, or whether the new bone is stored in mechanically optimal or less optimal regions of the skeleton, are open to discussion.

Influence of weight and gonadal status on total and regional bone mineral content and on weight-bearing and non-weight-bearing bones, measured by dual-energy X-ray absosorptiometry

OBJECTIVE

To evaluate the influence of weight on total body bone mineral content (BMCTB) and regional body bone mineral content (head, arms, trunk and legs). This was studied in accordance with gonadal status and the weight-bearing or non-weight-bearing status of each region.

METHODS

The study included 94 postmenopausal women (mean age 60.6 +/- 10.5 years), 36 perimenopausal women (mean age 49.0 +/- 2.3 years) and 60 premenopausal women (mean age 36.1 +/- 6.9 years). Full-body bone densitometry (DXA), for measuring total body bone and regional bone mineral content, was carried out in all the women.

RESULTS

Among these groups, the influence of 1 kg of body weight on total and regional bone mineral content (percent) did not differ (paired test P ns). In the overall group of women, paired comparison showed differences between the head and other zones measured (P = 0.036-0.004). In the overall group of women, no differences were found in the percent influence of 1 kg body weight on bone mineral content in any study zone (by ANOVA, Fisher's PLSD post hoc test and the Kruskal-Wallis test). In the overall group of women, Fisher's r to z test revealed a non-significant relationship between weight and the bone mineral content of the head (r = 0.49, P ns) but in every other region the relationship between weight and bone mineral content was significant (r = 0.36-0.54, P < 0.0001 in all).

CONCLUSIONS

The effect of body weight on BMCTB and regional did not differ significantly with either gonadal status or weight-bearing (legs) and non-weight-bearing bones (arms).

Age-related changes in body composition of healthy and osteoporotic women

OBJECTIVES

The study was carried out to assess age-related changes of body composition and to evaluate the influence of lean and fat mass in bone mineral density of healthy and osteoporotic women.

METHODS

166 healthy women in premenopause (43.2 +/- 6.7 years), 591 healthy postmenopausal women (59.9 +/- 8.1 years) and 373 women with established involutive osteoporosis (66.2 +/- 7.8 years) were evaluated: bone mineral density (BMD) and soft tissue composition (fat mass, lean mass) were measured by a total body Lunar DPX device.

RESULTS

no difference in lean mass was appreciated between the groups. Fat mass was significantly lower in premenopausal women (19.5 +/- 6.5 kg) and osteoporotic patients (18.8 +/- 5.2 kg) than in postmenopausal healthy women (21.8 +/- 5.7 kg). In premenopause weight, soft tissue mass and fat mass increased with age (P < 0.05). In postmenopause, lean mass decreased significantly in healthy women (P < 0.05). Fat mass was lower in the osteoporotics than in normals. Total BMD correlated significantly with fat and lean mass in all groups (P < 0.01). BMD/height ratio correlated significantly with fat mass (P < 0.01), not with lean mass.

CONCLUSIONS

BMD is closely related to fat mass in healthy premenopausal and postmenopausal women, and in osteoporotic patients; osteoporotic patients and healthy premenopausal women are characterized by a lower fat mass than healthy postmenopausal women; fat mass may be considered one of the determinants of bone mass also in involutive osteoporosis.

Ultrasound bone velocity on proximal phalanges in premenopausal, perimenopausal, and postmenopausal healthy women

RATIONALE AND OBJECTIVES

The authors studied premenopausal, perimenopausal, and postmenopausal women to determine if ultrasound bone velocity (UBV) on proximal phalanges of women reflect bone changes related to gonadal status and age.

METHODS

A total of 166 healthy women-64 postmenopausal women (mean age 58.7 +/- 9.4 years), 41 perimenopausal women (mean age 49.5 +/- 2.9 years), and 61 premenopausal women (mean age 36.8 +/- 7.1 years)-were studied. All the women underwent UBV study of the 2nd to 5th proximal phalanges on the nondominant hand and the mean value of all ultrasound measurements was calculated.

RESULTS

The postmenopausal women had a UBV that differed significantly, one-way analysis of variance, from that of the perimenopausal women and premenopausal women (both P < 0.001). The UBV measurements of the perimenopausal women differed significantly from those of the premenopausal women (P < 0.01). Simple linear regression analysis of the relation between UBV and age showed that this was significant and negative in the overall group of women (r = -0.69; P < 0.0001), significant in the perimenopausal (r = -0.66; P < 0.001) and postmenopausal women (r = -0.69; P < 0.001) and nonsignificant in the premenopausal women (r = 0.08; P not significant). In the postmenopausal women, the correlation between UBV and years since menopause was larger (r = -0.71; P < 0.0001) than the correlation between UBV and chronological age.

CONCLUSIONS

Ultrasound bone velocity of the phalanx, as a method for measuring changes in bone with age, has a precision that makes it possible to detect changes in bone mass in perimenopausal women and may perform similarly to other bone mass measurements.

Weight, body composition, and bone density in postmenopausal women

Associations of body weight and body composition with bone mineral density (BMD) were examined in 261 postmenopausal women. BMD, body fat, and body nonfat soft tissue (NFST) were measured by dual-energy X-ray absorptiometry (DXA). A height-independent BMD variable (HIBMD) was calculated to correct for differences among individuals in bone thickness, a dimension that is ignored by DXA scanners. HIBMD was calculated as BMD divided by height at the spine and femoral neck, and BMD divided by the square root of height at the total body. Weight, fat, and nonfat soft tissue were all positively correlated with both BMD and HIBMD, but the magnitudes of regression and correlation coefficients were lower when HIBMD was the dependent variable. The weight-independent associations of body composition with HIBMD were examined by including weight and % NFST together in linear models. In these analyses, weight was positively associated with HIBMD at all three skeletal sites (r = 0.22-0.26, P < 0.05), % NFST was not associated with HIBMD at the spine or femoral neck (r = 0.01-0.02), and there was only a weak inverse correlation of % NFST with total body BMD (r = -0.12, P < 0.05). These findings are consistent with those of previous studies demonstrating positive associations between body weight and BMD. In addition, they demonstrate that once bone thickness and body weight are taken into account, body composition appears to have little if any independent effect on bone density at the skeletal sites measured. This finding is consistent with the hypothesis that the protective effect of body weight is brought about predominantly through its mechanical force on the skeleton.

Development of mass, density, and estimated mechanical characteristics of bones in Caucasian females

Three hundred and thirty healthy Finnish girls and premenopausal women, aged 7-47 years, were examined to evaluate the natural development of bone mineral mass and density from early childhood to menopause. Bone mineral content (BMC,g) and areal density (BMD, g/cm2) were measured from the spine (L2-L4), femoral neck, trochanter region of the femur, and distal radius using dual-energy X-ray absorptiometry (DXA). In addition, the bone mineral apparent density (BMAD, g/cm3) was assessed from the above described skeletal sites, and the mechanical competence of the femoral neck was estimated. Special attention was paid to the timing of the peak values of these bone parameters as well as to the evidence of premenopausal bone loss. The BMC, BMD, and BMAD of the spine, femoral neck, and trochanter region of the femur achieved peak values around the age of 20, and the bone loss seemed to start soon thereafter. In contrast, the bone mass of the distal radius slightly increased between the ages of 20 and 47. In the femoral neck, the estimated bending strength achieved its peak value around the age of 20 and showed a slight decrease during the following decades. The highest body weight and neck-length adjusted strength values of the femoral neck were, however, found in early childhood, with the values decreasing linearly thereafter. In conclusion, this study supports previous findings of rapid bone mineral accumulation in late adolescence, and occurrence of the peak bone mass and density around the age of 20. Premenopausal bone loss seems to occur in the proximal femur and lumbar spine. Our observations of femur strength development imply that from childhood to menopause the mechanical strength of the femoral neck is well adjusted to the biomechanical loading requirements of the body.

Menopause, fat and lean distribution in obese women

OBJECTIVES

Whether menopause per se influences fat distribution independently of the effect of aging remains controversial. The lack of consistency in the menopause related changes in body fat distribution may be the result of differences in the methods for measuring fat distribution or in the characteristics of the women studied. The aim of this cross sectional study in obese women was to compare total body composition and regional fat and lean distribution, in premenopausal, perimenopausal and postmenopausal women.

METHODS

Body composition was assessed by dual energy X-ray absorptiometry (DEXA) in premenopausal (n = 26), perimenopausal (n = 24) and postmenopausal (n = 73) obese women with no intercurrent diseases.

RESULTS

It was shown that postmenopausal obese (n = 73) women had a higher proportion of total fat mass in the trunk and a lower proportion of total fat and lean mass in the femoral and leg regions than premenopausal women after adjustment for age and total fat mass. In the same analysis, perimenopausal women had a lower proportion of total fat in the leg and femoral regions and of total lean in the femoral region than premenopausal women; they had a regional body composition similar to that of postmenopausal women.

CONCLUSION

The present data indicate that in obese women, post menopause and perimenopause are associated with differences in fat and lean distribution, independently of age and total fat.

Behavior of bone mass measurements. Dual energy x-ray absorptiometry total body bone mineral content, ultrasound bone velocity, and computed metacarpal radiogrammetry, with age, gonadal status, and weight in healthy women

RATIONALE AND OBJECTIVES

Bone mass as measured by dual energy x-ray absorptiometry varies with body weight. The authors studied the behavior of bone mass measurements made by ultrasound bone velocity and metacarpal radiogrammetry in relation to body weight.

METHODS

Eighty healthy women were studied: 40 post-menopausal and 40 premenopausal (mean age 60 +/- 6 and 38 +/- 8 years, respectively). The authors performed in every subject the following studies: a radiograph of the nondominant hand for metacarpal cortical thickness, a study of the 2nd to 5th proximal phalanges for ultrasound bone velocity, and total bone mineral content by dual energy x-ray absorptiometry.

RESULTS

The measurements obtained with the three methods correlated significantly with each other (P < 0.0001). The only parameter related significantly with weight were total bone mineral content (P < 0.0001). In the premenopausal women, age did not correlate with any measurement. In the postmenopausal women, age correlated significantly with the three measured parameters (P < 0.0058 to P < 0.0001).

CONCLUSIONS

Weight did not influence ultrasound bone velocity and metacarpal cortical thickness measurements.

Changes in the cortical and trabecular bone compartments with different types of menopause measured by peripheral quantitative computed tomography

Our objective was to study the changes in the bone mineral density of the cortical and trabecular compartments with different types of menopause. A total of 153 normal postmenopausal women (mean age 48 +/- 5 years) were studied. The women were divided into three groups based on mean age at menopause: early menopause (menopause before 43 years), normal menopause (menopause at 44-52 years), and late menopause (menopause after 52 years). The number of years since menopause was similar in all three groups (+/- 5 years). Cortical and trabecular bone mineral density was determined in all the women using peripheral quantitative computed tomography. Our results show that only the trabecular bone mineral density differed significantly among the groups (Kruskal-Wallis: P = 0.0029). The women with early menopause had a lower trabecular bone density than the women with normal and late menopause (P = 0.0019 and P < 0.0001, respectively). Among the women with early menopause, 22 had experienced menopause before the age of 40 and 25 after the age of 40; there were significant differences in trabecular bone mineral density between these two subgroups (P < 0.05). Trabecular bone mineral density, the only variable studied that varied among the groups, correlated significantly with the duration of reproductive life (simple linear regression: r = 0.340, P < 0.0001). In conclusion, these findings emphasize the importance of the duration of reproductive life as a determinant of bone mass in women.

Effect of bone density of the head on total body DEXA measurements in 100 healthy Swedish women

PURPOSE

The aims of this study were to examine the bone areal density of the head and how it varied in relation to the density of the rest of the skeleton, and with age, and body mass index (BMI). Our intention was to study the feasibility of excluding the head from the rest of the body, a method which might improve the fracture prediction power of bone mineral measurements.

MATERIAL AND METHODS

Bone mineral per area (BMA) and bone mineral content (BMC) (g) were determined in 100 consecutive female volunteers, aged 17 to 78 years, with total and partial body measurements.

RESULTS

BMC of the head was found to be 20.2 +/- 2.2% of that for the total body. The BMA of the head was 2.38 +/- 0.21 times higher than that of the rest of the body. The correlation between the BMA of the head and the rest of body was significant (r = 0.73). The average change in z-score (referred to the same age group in our material) was 0.20 when the head was excluded from total body BMA. The BMA of a) total body, b) total body, head excluded, and c) head decreased with age. The BMA of the head was correlated to BMI in the older age groups (p < 0.01). The relative statistical uncertainty for repeated measurement of head BMA was 1.8%.

CONCLUSION

The change of the bone density of the head with age and BMI, in comparison to that of the rest of the skeleton, suggests that when the head is excluded from total body BMA better predictive value for fracture risk is obtained.

Ultrasound velocity changes at the proximal phalanxes of the hand in pre-, peri- and postmenopausal women

We evaluated the bone tissue modifications which occur in pre-, peri- and postmenopausal women by means of an ultrasound (US) device which measures US propagation velocity in the distal metaphysis of the proximal phalanxes of the hand. Before starting the study, two operators assessed the in vivo short-term precision of the device in 12 volunteers, each measured 10 times (5 times by each operator). Then the US velocity in the dominant (DO) and non-dominant (ND) hand was measured in 228 women to evaluate whether there was a difference between US values measured at these sites. Finally, another selected group of 417 healthy pre-, peri- and postmenopausal women, aged from 40 to 65 years, was studied to evaluate the physiological climacteric changes in the US parameter measured: amplitude-dependent speed of sound (AD-SoS). In the 12 volunteers, intra- and inter-observer short-term precision (CV) was 0.4% (for both the operators) and 1.0%, respectively. DO and ND hand AD-SoS values (2074.1 +/- 63.8 m/s and 2077.1 +/- 65.5 m/s, respectively) proved to be highly correlated (r = 0.96, p < 0.0001) in the 228 women studied. AD-SoS distribution (417 subjects) was correlated with age, climacteric condition (premenopause with regular or irregular cycles and natural postmenopause) and body mass index (BMI). In premenopause (253 subjects) the US velocity was higher among women with regular cycles (2107.2 +/- 48.5 m/s) than among those with irregular cycles (2074.7 +/- 44.1 m/s) (p < 0.0001). In postmenopause (164 subjects) an inverse correlation between AD-SoS and the time elapsed since menopause was found (r = -0.42, p < 0.0001). Furthermore, age and BMI were shown to be inversely related to AD-SoS (r = -0.47, p < 0.0001 and r = -0.30, p < 0.0001, respectively) when evaluated in the whole study group. The results obtained confirm that US transmission at the phalanxes is sensitive to pre-, peri- and postmenopausal bone changes. Further studies are needed to evaluate its ability to predict osteoporotic fracture risk.

Correlation of total-body bone mineral content determined by dual-energy X-ray absorptiometry with bone mineral density determined by peripheral quantitative computed tomography

RATIONALE AND OBJECTIVES

We sought to determine the value of peripheral quantitative computed tomography (pQCT) in measuring bone mineral density.

METHODS

In 50 healthy, eugonodal premenopausal women, we correlated measurements of total bone mineral content (BMCTB), made with dual-energy X-ray absorptiometry (DXA), and bone mineral density, determined by pQCT.

RESULTS

The partial correlations, adjusted for weight and age, between BMCTB and cortical bone density, total bone density, and trabecular bone density were .71 (p < .0001), .63 (p < .0001), and .32 (p < .05), respectively.

CONCLUSION

These results and the advantages of pQCT--providing precise bone density determinations for trabecular and compact bone separately, having a high spatial resolution that allows a "compartmental" analysis of bone structure, having a low coefficient of variation, and having a minimal radiation dose (< 5 mrem)--confirm the adequacy of using this method for bone mass studies.

The BsmI vitamin D receptor restriction fragment length polymorphism (BB) predicts low bone density in premenopausal black and white women

We conducted a study to determine whether a recently described restriction fragment length polymorphism in the vitamin D receptor gene (VDR-RFLP) predicts bone mineral density (BMD) in unrelated, premenopausal women as well as to determine the racial contribution to any genotypic influences on BMD. White (n = 83) and black (n = 72) women between 20 and 40 years of age were genotyped based on the presence (b) or absence (B) of a BsmI restriction enzyme site in the VDR gene, and BMD in the lumbar spine and femur neck was determined for each subject. There were 16 BB, 73 Bb, and 66 bb women. No significant difference was observed in genotypic distribution between the racial groups. The interaction of race by genotype on age- and body mass index (BMI)-adjusted BMD was not significant at either site. Age- and BMI-adjusted BMD was higher in black women at the spine (by 7.2%, p = 0.046) and femur neck (7.3% higher, p = 0.004). In the group as a whole, mean BMD in the femur neck was lower in the BB women that the bb (by 8.1%, p = 0.034) or Bb women (by 9.3%, p = 0.015) after controlling for age, BMI, race, and the race by genotype interaction. Adjusted lumbar spine BMD was lower in the BB women than the Bb women (6.4% lower, p = 0.036) in the group as a whole. No difference were detected between Bb and bb women at either site. A similar pattern of low BMD at the femur neck and the lumbar spine was seen in BB women of both races.(ABSTRACT TRUNCATED AT 250 WORDS)

Age- and menopause-associated variations in body composition and fat distribution in healthy women as measured by dual-energy X-ray absorptiometry

To assess the variation with age and menopause, 407 healthy normal women aged 18 to 75 years had body composition and fat distribution measured by dual-energy x-ray absorptiometry (DEXA). The mean +/- SD are given for different age decades. Postmenopausal women had significantly more fat, a more central fat distribution, and less lean tissue mass (LTM) than premenopausal women. In premenopausal and postmenopausal women, age only correlated with the abdominal to total-body fat tissue ratio (r approximately .24, P < .05), whereas the years since onset of menopause correlated with fat tissue mass (FTM), fat%, abdominal fat%, and the abdominal to total-body fat tissue ratio (r approximately .2, P < .05). To assess the independent impact of age, menopausal status, and years since menopause, multiple linear regressions were performed. FTM, fat%, and abdominal fat% were significantly related to menopausal status and years since menopause independently of age. The abdominal to total-body fat tissue ratio was statistically significantly related to age, but tended also to be independently related to years since menopause. LTM was statistically significantly related to menopausal status independently of age and years since menopause. In summary, we suggest that in healthy women total-body and abdominal fat may increase and LTM may decrease in the years after menopause, primarily in the perimenopausal years, without significant changes before menopause.

Bone density in young women is associated with body weight and muscle strength but not dietary intakes

Potential determinants of bone mineral density (BMD) were studied cross-sectionally in 115 healthy, sexually mature Caucasian women aged 18 years. Bone mineral density (Hologic QDR1000W) of the lumbar spine, proximal femur (five sites), and distal tibia and fibula; fasting blood and urine calcium biochemistry; serum sex hormone levels (follicular phase); nutrient intakes; aerobic fitness; trunk muscle strength; and habitual activity levels were measured. The effects of heredity were considered by measuring the BMD of 107 of the subjects' mothers. Simple and stepwise regression analysis were used to identify significant determinants of BMD at each of the regions studied. The analysis indicated that significant bivariate correlations exist between BMD at all sites and body weight (r = 0.23-0.47, p < or = 0.01), lean body weight (r = 0.34-0.46), trunk strength (r = 0.27-0.47), physical activity score (r = 0.20-0.25), and aerobic fitness (r = 0.29-0.45). Dietary calcium intake correlated significantly with BMD at the trochanter site only (r = 0.19), and none of the biochemical or hormonal indices measured correlated consistently with BMD at any site. Significant correlations between the BMD of mothers and daughters ranged from r = 0.43 at lumbar spine to r = 0.34 at the intertrochanteric site. Paired t-tests showed the daughters had significantly (p < 0.03) lower BMD than their mothers at the lumbar spine (98 +/- 12% [mean +/- SD]) and significantly higher (p < 0.002) BMD at the femoral neck, trochanter, and total hip sites (110 +/- 16%, 108 +/- 17%, 103 +/- 14%, respectively). When stepwise regression analysis included weight-corrected strength of the trunk flexor muscles (Corr Flex), weight-corrected aerobic fitness (Corr VO2max), physical activity score, and body weight, body weight was the only significant determinant of BMD at all sites. Corr Flex made significant contributions at all sites except the femoral neck, while Corr VO2max made additional contribution at the femoral neck, trochanter, total hip, and shaft of femur sites. These variables accounted for 13-27% of the variance in BMD. The addition of mother's BMD to these independent variables, in stepwise regression analysis, improved the prediction to 18-31% of the variance.

Influence of weight and seasonal changes on radiogrammetry and bone densitometry

We studied the behavior of radiogrammetric and densitometric measurements in relation to season and body weight in a group of 30 healthy premenopausal women. Measurements were made at 6-month intervals, in summer/fall when bone density increases and in winter/spring when bone density declines. Total body bone mineral content (TBBMC) and regional bone mineral content (RBMC) were measured using dual-energy X-ray absorptiometry (DXA). Metacarpal radiogrammetry was carried out with computed radiography. Weight and body mass index increased significantly in winter (P < 0.05) and total body and RBMC decreased (P < 0.001). The opposite occurred in summer: weight and body mass index decreased significantly (P < 0.05) and total body and regional bone mineral content increased (P < 0.001). Differences in TBBMC persisted when the measurement was corrected for weight (TBBMC/W) (P < 0.001), but not for metacarpal cortical thickness corrected for weight. In the first measurement made there were significant relations between weight and both TBBMC (P < 0.001) and metacarpal cortical thickness (P < 0.005). The relation between weight and TBBMC remained significant in later measurements, but the relation between weight and metacarpal cortical thickness ceased to be significant in the second and fourth measurements. Our results show that there is an important seasonal variation in bone mass and that DXA is more sensitive than radiogrammetry in registering these changes.